Hundreds of years before it happened, Isaiah spoke of one that would have a voice crying in the wilderness to prepare the way of the LORD.
Matthew 3:3
For this is he who was spoken of by the prophet Isaiah, saying:
“The voice of one crying in the wilderness:
Prepare the way of the LORD;
Make His paths straight.’ ”
John the Baptist was there to prepare a way in the hearts of mankind to receive the coming King. Advent is a reminder to prepare a way in our hearts to the celebration of Jesus’s birth. The fact He came to earth for us, to redeem us.